<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>1.外间距测试</title>
    <style>
        body{
            margin: 0;
        }
        .fu{
            overflow: hidden;
            background-color: rgba(255,255,3,0.5);
        }
        .fu>div{
            width: 100px;
            height: 100px;
            background-color: rgba(0,0,255,6);
        }
        .z1{
            margin-top: 50px;
            margin-bottom: 10px;
        }
        .z2{
            margin-top: 30px;
        }
        .z3{
            margin: 0 auto;
        }
        .z4{
            margin-bottom: 30px;
        }
        span{
            border: red solid 5px;
        }
        .s1{
            margin: 30px 20px;
        }
    </style>
</head>
<body>

    <span class="s1">span1</span>
    <span class="s2">span2</span>
    <span>span3</span>

    <div class="fu">
        <div class="z1">子元素div1</div>
        <div class="z2">子元素div2</div>
        <div class="z3">子元素div3</div>
        <div class="z4">子元素div4</div>
    </div>

</body>
</html>